Abstract: The homozygote transgenic lines GO-2 with the up-regulated GLDH ( the key enzyme that catalyzes the final step of Asc biosynthesis in plants) gene and GI-2 with the down-regulated GLDH gene had been established from the cultivar Zhong Hua11 (ZH-11). Treatment three rice cultivars with methyl viologen(MV) and the effect of changes of endogenous ascorbic acid on resistance to oxidative stress of rice (Oryza sativa) was investigated among three rice cultivars of ZH-11, GO-2 and GI-2. After treatment with MV photo-oxidation, Superoxide anion and H2O2 were lower in GO-2 than in ZH-11 or GI-2. GI-2 was the weakest when membrane was oxidized, soluble protein was degraded in three rice cultivars. Changes of chlorophyll fluorescence quenching in three rice cultivars showed GO-2 is stronger than ZH-11 or GI-2. Those results showed GO-2 can resistance more oxidative stress, proved ascorbic acid was important for rice resistance to oxidative stress.